I agree with the last part. I agree with the first part if you try to play too strong a flex, but if you get the right setup they feel nicer than anything I've ever hit and have great control. I had the X flex soft stepped at first in my test club, then briefly tried the X straight in for about a round, and the results were terrible. The half flex makes a huge difference in results and makes the shaft perform great on all kinds of shots, and I have the swing speed to hit about anything in all my other clubs. I play stout X flexes and lowish lofts in my woods and load them easily but the C taper is built to handle powerful swings. Justin Rose and others on tour tend to favor the S+ flex despite hitting X in everything else and swinging over 115mph with the driver. Even Furyk isn't a long hitter, but still a tour pro and he went with the R+ and I believe he shot 59 with them.
They have a profile to them that's unlike a lot of others. This isn't a shaft that caters to "tweener" X flex types in the market. Kim Braly has hinted that they play about a half flex stiffer than the tours, and I'd certainly agree based on my usage.
The C tapers are meant for those who seriously load the shaft and often have fast tempos. Personally I'm fairly smooth but I have a very fast and high launching swing without excessive spin. Even if you can hit the X in the tours comfortably, I'd think the S+ tapers would still play a bit stiffer if anything. Personally I figured I could handle about an S+ with certainty based on my SS numbers and distances, but I thought I might be able to go a bit stiffer because I hit the ball high, so I got the X soft stepped because I wanted the heavier weight. I don't doubt for a second that the S+ would be sufficient for me though, but I'm not buying another set and tossing aside my best asset to find out.
I'd also like to mention that I love them in my 3 iron through pitching wedge and get plenty of spin in my short clubs for my needs, but I went with the KBS wedge shaft in my 54 and 60 which is a little known but very nice shaft. It's unique from the tours and the Hi Rev, and comes in a nifty black finish as well. I didn't compare it apples to apples in the same head vs the tapers, but I do have one C taper wedge shaft left over... But I like them how they are for now.